1. Field of the Invention
The invention relates to micromechanical sensors (also referred to as MEMS sensors) such as micromechanical accelerometers, micromechanical rate of rotation sensors and micromechanical sensors with comb drives.
More particularly, this invention pertains to an operating method and circuit for operating a capacitive micromechanical sensor having at least one differential capacitor formed by two stationary electrodes and a movable center electrode arranged between the latter and suspended in a resilient manner that can be deflected by an external force whose deflection is measured with opposite and equal excitation voltages being applied between the stationary electrodes and the center electrode.
2. Description of the Prior Art
In its basic variant, a MEMS sensor comprises a differential capacitor whose center electrode is resiliently suspended to react, with deflection, to forces acting upon it. The deflection is measured by corresponding known circuit measures. In a resetting system (closed-loop arrangement), the measured value is supplied to a controller that influences electrostatic forces acting on the plates of the differential capacitor to compensate the external acceleration force. This operation is referred to as a reset. The reset is perfect if the deflection of the center electrode becomes “0”.